1. Field of the Invention
This invention relates to a method of subjecting a high-level radioactive liquid waste to a vitrification treatment by using cold-crucible induction melting.
2. Description of Related Art
A high-level radioactive liquid waste generated from a reprocessing plant is subjected at present to a vitrification or glassification treatment. The reasons why glass is used are because (1) glass is capable of uniformly solid-solving or dispersing almost all components of waste, (2) glass has an excellent stability, and (3) an industrial glass manufacturing method can be applied to manufacture the glass to be used.
In order to obtain a vitrified body, a glass melting furnace of a directly supplied current type has heretofore been used. Concretely speaking, a mixture of a high-level radioactive liquid waste and a raw glass material is charged into the melting furnace, and the glass is melted by applying heat thereto by using a preheater. When an electric current is supplied between electrodes disposed in the melting furnace, it flows into the molten glass, which is thereby heated to keep all of the materials charged into the furnace melted.
In the conventional melting technique, glass, an object material to be melted contacts directly a structural material (refractory furnace wall and crucible wall) of a melting apparatus under the object material melting temperature conditions. Therefore, the conventional technique poses important problems including the measures for preventing the high-temperature corrosion of the structural materials (i.e. provision of a margin for corrosion or replacement of the structural materials) and limitation on a melting temperature (i.e. setting the highest temperature, at which the strength of the structural materials can be secured, as an upper limit).